System and method for determining an output of an electromagnetic wave based on image information

ABSTRACT

A system includes a transmission unit configured to generate an electromagnetic wave, a first reception unit configured to detect the electromagnetic wave, and a processing unit configured to determine whether an output of the electromagnetic wave from the transmission unit is more than or equal to a threshold based on first image information obtained by capturing an image of the transmission unit in a state where the transmission unit is irradiating the electromagnetic wave.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

The aspect of the embodiments relates to a terahertz wave camera system.

Description of the Related Art

Japanese Patent Application Laid-Open No. 2018-087725 discusses a camerasystem to which a terahertz wave is applied. Specifically, JapanesePatent Application Laid-Open No. 2018-087725 discusses an activeterahertz wave camera system having a configuration in which a terahertzwave is generated from a plurality of terahertz wave light sources, anobject is irradiated with the terahertz wave, and then the terahertzwave reflected by the object is detected.

SUMMARY OF THE DISCLOSURE

According to an aspect of the embodiments, a system includes atransmission unit configured to generate an electromagnetic wave, afirst reception unit configured to detect the electromagnetic wave, anda processing unit configured to determine whether an output of theelectromagnetic wave from the transmission unit is more than or equal toa threshold based on first image information obtained by capturing animage of the transmission unit in a state where the transmission unit isirradiating the electromagnetic wave.

According to another aspect of the embodiments, a method for a systemincludes acquiring first image information obtained by capturing animage of a transmission unit in a state where the transmission unit isirradiating an electromagnetic wave, and determining whether an outputof the electromagnetic wave from the transmission unit is more than orequal to a threshold based on the first image information.

Further features of the disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration of a camerasystem according to a first exemplary embodiment.

FIGS. 2A and 2B are schematic diagrams each illustrating an imagecaptured by the camera system according to the first exemplaryembodiment, and FIG. 2C is a schematic graph illustrating a method forprocessing therefor.

FIGS. 3A and 3B are flowcharts each illustrating an operation to beexecuted by the camera system according to the first exemplaryembodiment.

FIG. 4A is a schematic diagram illustrating a configuration of a camerasystem according to a second exemplary embodiment, and FIG. 4B is aschematic diagram illustrating an image captured by the camera systemaccording to the second exemplary embodiment.

FIG. 5A is a schematic diagram illustrating a configuration of a camerasystem according to a third exemplary embodiment, and FIGS. 5B and 5Care schematic diagrams each illustrating an image captured by the camerasystem according to the third exemplary embodiment.

FIG. 6 is a schematic diagram illustrating a configuration of a camerasystem according to a fourth exemplary embodiment.

FIG. 7 is a schematic diagram illustrating a configuration of a camerasystem according to a fifth exemplary embodiment.

FIGS. 8A, 8B, 8C and 8D are schematic diagrams each illustrating animage captured by the camera system according to the fifth exemplaryembodiment.

DESCRIPTION OF THE EMBODIMENTS

A terahertz wave is an electromagnetic wave in an invisible wavelengthband and thus is not visible to human eyes. Accordingly, it is difficultfor a human to visually check whether a terahertz wave at a desiredfrequency is generated from a light source.

Thus, if a malfunction occurs in a light source or a system and adesired terahertz wave is not generated from the light source, it isdifficult to normally capture an image of an object. Additionally, aterahertz wave at an unintended frequency may be generated by anoscillation due to a parasitic capacitance in a circuit of the lightsource. In this case, an amount of current that is substantially equalto an amount of current to flow during a normal operation flows to thecircuit of the light source. For this reason, the abnormality cannot bedetected even by monitoring the current flowing to the light source.Thus, some measures to check the operation of a light source of theterahertz wave are to be provided.

A terahertz wave will be described. A terahertz wave is a radio wavetypically having a frequency band from 0.1 THz to 30 THz. A terahertzwave has a longer wavelength than visible light and infrared light, andthus is less affected by scattering of light from an object and has highpermeability to many substances. The wavelength of a terahertz wave isshorter than that of a millimeter wave, so that a high spatialresolution can be obtained. By taking advantage of thesecharacteristics, applications to a safe imaging technique usingterahertz waves in place of X-rays are expected. Specific examples ofthe expected applications to the imaging technique include a securitycheck and a surveillance camera in a public place.

Exemplary embodiments will be described in detail below with referenceto the accompanying drawings. The following exemplary embodimentsillustrate an example where a terahertz wave camera system is used as acamera system. Each of the terahertz wave camera systems according tothe exemplary embodiments can be applied to a security check and asurveillance camera, which are examples of the expected applications.The following exemplary embodiments are not intended to limit thedisclosure. Multiple features are described in the exemplaryembodiments. However, not all of these features are essential to thedisclosure, and multiple such features can be combined as appropriate.In the accompanying drawings, the same or like components are denoted bythe same reference numerals, and redundant descriptions are omitted.

A camera system 1001 according to a first exemplary embodiment will bedescribed with reference to FIGS. 1 to 3B.

FIG. 1 is a schematic diagram illustrating a configuration example ofthe camera system 1001. The camera system 1001 includes a reception unit100, a transmission unit 103, a transmission unit 104, a transmissionunit 105, a display unit 111, and a processing unit 110. In the camerasystem 1001 according to the present exemplary embodiment, thetransmission units 103 to 105 are disposed at positions within a fieldangle where terahertz waves from the transmission units 103 to 105 canbe received by the reception unit 100.

The transmission units 103 to 105 each irradiate an object 109 with aterahertz wave. The term “irradiation” used herein can also be referredto as radiation. The camera system 1001 includes a plurality oftransmission units. However, the number of transmission units is notlimited to three and the camera system 1001 can include any number oftransmission units. For example, the number of transmission unitsincluded in the camera system 1001 can be one, two, or 16 or more. Thefrequency of a terahertz wave irradiated from each of the transmissionunits 103 to 105 includes any frequency components or a single frequencyin a range from 0.1 THz to 30 THz. In a case where a human body isincluded as the object 109, many clothes have high permeability up to 1THz. Accordingly, for example, in a case where the camera system 1001 isused for a concealed-object inspection, a terahertz wave in a frequencyband from 0.3 THz to 1 THz can be used. Assume that, in the presentexemplary embodiment, a frequency band including 0.45 THz is used. Alsoassume that the object 109 is moving along a movement direction 112.

In the transmission unit 103, a plurality of transmitters 106, each ofwhich emits a terahertz wave, is disposed. For example, in thetransmission unit 103, the transmitters 106 are disposed in an array of2×2. In the transmission unit 104, a plurality of transmitters 107, eachof which emits a terahertz wave, is disposed. For example, in thetransmission unit 104, the transmitters 107 are disposed in an array of2×2. In the transmission unit 105, a plurality of transmitters 108, eachof which emits a terahertz wave, is disposed. For example, in thetransmission unit 105, the transmitters 108 are disposed in an array of2×2. The layout method and the number of the transmitters 106, 107, and108 can be appropriately selected depending on the intensity and adirectivity of terahertz waves.

The transmitters 106, 107, and 108 are each composed of one or moretransmission elements, and are each mounted on a casing as a singlechip. The casing is also referred to as a package or a mount member.Examples of the transmission elements can include a terahertz wavetransmission element of a semiconductor element such as a resonanttunneling diode, and a photoexcitation terahertz wave transmissionelement. In one embodiment, each of the transmission elements includesan antenna structure so that impedance matching with atmosphere andterahertz wave generation efficiency can be improved. The size of theantenna structure is designed to be substantially equal to a wavelengthto be used.

The reception unit 100 is an element that can detect a terahertz wave.The reception unit 100 can also be referred to as a terahertz wavecamera. The reception unit 100 includes a receiver 102 and an opticalsystem 101. The receiver 102 is a sensor that is partitioned by aplurality of pixels. The optical system 101 focuses a terahertz wave ona reception surface of the receiver 102. Further, the optical system 101can image the terahertz wave on the reception surface of the receiver102. The reception unit 100 has a configuration similar to a camera inwhich the receiver 102 and the optical system 101 are integrallymounted. However, the reception unit 100 can have a configuration inwhich the receiver 102 and the optical system 101 are stored in separatecasings, respectively, and are installed in combination.

The receiver 102 is composed of one or more reception elements, and ismounted on a casing as a single chip. The casing is also referred to asa package or a mount member. Examples of the reception element caninclude a thermal detection element such as a bolometer, and asemiconductor detection element such as a Schottky barrier diode. Sincethe reception unit 100 functions as a camera to detect an image, thenumber of reception elements can also be referred to as the number ofpixels, and the size of each reception element can also be referred toas a pixel size. For example, in a case where the camera system 1001 isused for a concealed-object inspection, 10,000 or more pixels are to beused. In other words, the receiver 102 can also be referred to as anarea sensor having 100 pixels×100 pixels. Since the wavelength of aterahertz wave is several hundred μm, the size of a single receptionelement is determined based on this value. In view of the above, thesize of the receiver 102 is typically 10 mm or more×10 mm or more. Inview of the resolution and size, the number of pixels to be used is20,000 pixels or more, and the size of the receiver 102 is several tensof mm or more on each side. The number of pixels to be used can be100,000 pixels or more, and the size of the receiver 102 can be 500 mmor more on each side. Further, in order to improve the impedancematching with atmosphere and detection efficiency of the terahertz wave,in one embodiment, each reception element includes an antenna structure.The size of the antenna structure is designed to be substantially equalto a wavelength to be used.

The optical system 101 images the terahertz wave on the receptionsurface of the receiver 102. The optical system 101 can be an opticalelement such as a lens or a mirror. In a case where a lens is used asthe optical system 101, it is to use, as a lens material, a materialwith a small loss against a terahertz wave to be used. Examples of thelens material can include Teflon® and high density polyethylene. Theoptical system 101 is an imaging optical system, and can be designed bya visible light method. A dashed-dotted line illustrated in FIG. 1represents an optical axis of the optical system 101. In one embodiment,the optical axis matches the center of mass of the reception surface ofthe receiver 102. An aperture diaphragm can be provided in the opticalsystem 101. A depth of focus of an object can be increased by stoppingdown the aperture diaphragm, i.e., by increasing an F-value. In otherwords, an object image in a wide range can be obtained. However, if theF-value is increased, the intensity of the terahertz wave that has beentransmitted through the optical system 101 may be decreased. In oneembodiment, the aperture is adjusted in view of the intensity of theterahertz wave from each of the transmission units 103 to 105.

The processing unit 110 is a processing apparatus such as a computerincluding a central processing unit (CPU), a memory, and a storagedevice. Image information acquired by the reception unit 100 is sent tothe processing unit 110, and the processing unit 110 performs signalprocessing on the image information. The functions of the processingunit 110 can be provided in the reception unit 100. The processing unit110 can perform determination processing to be described below andsignal processing, and can control overall operations of the camerasystem 1001. In other words, the processing unit 110 can include adetermination unit, a signal processing unit that processes signals, anda control unit. The processing unit 110 needs not necessarily be aprocessing apparatus such as a computer, but instead at least a part ofprocessing can be performed in a cloud system. Further, a part ofprocessing can be performed by an artificial intelligence (AI). Thepresent exemplary embodiment illustrates a configuration in which theprocessing unit 110 includes the determination unit, the signalprocessing unit, and the control unit. However, the determination unit,the signal processing unit, and the control unit can be separatelyprovided.

The display unit 111 can be a monitor of the computer of the processingunit 110, or can be prepared to display an image. The display unit 111displays an image based on the image information formed by theprocessing unit 110.

To facilitate explanation of the present exemplary embodiment, assumethat the following transmitters are provided in the configurationillustrated in FIG. 1 . Assume that a terahertz wave is not generatedfrom a transmitter 107 a of the transmission unit 104, or anelectromagnetic wave at a frequency different from a desired frequencyis generated due to a parasitic oscillation or the like. Also assumethat a transmitter 108 a of the transmission unit 105 generates aterahertz wave at a desired frequency, but the intensity of theterahertz wave is decreased. The transmitters 107 a and 108 a areillustrated for descriptive purposes assuming a case where a malfunctionoccurs in the transmitters.

FIGS. 2A and 2B are schematic diagrams each illustrating an imagecaptured by the camera system 1001 illustrated in FIG. 1 , and FIG. 2Cis a schematic graph illustrating a method for processing the image inFIG. 2B. FIG. 2A illustrates an image obtained by capturing an image ofthe object 109. This image capturing operation is performed in a mainimage capturing operation. For example, a concealed object is detectedfrom the captured image. The main image capturing operation indicates anoperation of capturing an image of an object. In the present exemplaryembodiment, the captured image indicates an image obtained by capturingan image in a direction perpendicular to the movement direction 112 ofthe object 109, that is, an image obtained by capturing an image of aside surface of the object 109. An image capturing direction can bechanged depending on the intended use. The image capturing direction canbe identified based on a direction of the optical axis of the opticalsystem 101. While the present exemplary embodiment assumes a case wherethe reception unit 100 detects a terahertz wave reflected by the object109, the reception unit 100 can also detect a terahertz wave that hasbeen transmitted through the object 109. Accordingly, positionalrelationships other than the positional relationship between thereception unit 100 and the transmission units 103 to 105, such as thepositional relationship between the reception unit 100 and the object109 and the positional relationship between the object 109 and thetransmission units 103 to 105, can be changed as appropriate.

FIG. 2B illustrates a captured image of the transmission units 103 to105. This image is captured in a state where the object 109 is notpresent, or in a state where the object 109 is located outside of arange of the field angle of the reception unit 100. The imageillustrated in FIG. 2B indicates a two-dimensional distribution of lightand dark images depending on the intensity of the terahertz wavegenerated from each of the transmission units 103 to 105. As theintensity increases, a lighter image can be obtained. In the imageillustrated in FIG. 2B, the portions respectively corresponding to thetransmission units 103 to 105 and the transmitters 106 to 108illustrated in FIG. 1 are denoted by the same reference numerals. Inthis case, the contrast of the images respectively corresponding to thetransmitters 107 a and 108 a is different from that of the imagesrespectively corresponding to the transmitters 106 to 108. FIG. 2C is aschematic graph illustrating an output of a terahertz wave at a locationindicated by a broken line 212 illustrated in FIG. 2B. A vertical axisrepresents an output. This output can also be referred to as anintensity.

A portion corresponding to the transmitter 107 a illustrated in FIG. 2Bis dark, and no signal is present in a desired terahertz wave band. Theoutput corresponding to the transmitter 107 a illustrated in FIG. 2C is“0”. Accordingly, it is obvious that the transmitter 107 a does notgenerate a terahertz wave at a desired frequency. A portioncorresponding to the transmitter 108 a illustrated in FIG. 2B is lighterthan the portion corresponding to the transmitter 107 a, but is darkerthan the other portions. The output corresponding to the transmitter 108a illustrated in FIG. 2C is lower than the other outputs. Therefore, itis obvious that the transmitter 108 generates a terahertz wave at adesired frequency, but the intensity of the terahertz wave is decreased.

Examples of a method for detecting a decrease in the intensity include amethod in which an allowable lower-limit threshold 213 is preliminarilydetermined as illustrated in FIG. 2C and a determination is made basedon whether the intensity is lower than the threshold. The output can beobtained based on an output intensity in a one-dimensional directionindicated by the broken line 212 in FIG. 2B, or can be set based on anoutput in each area identified from the image illustrated in FIG. 2B. Asthe output in each area, any value, such as a combined value of outputsfrom pixels in each area, or an average value of outputs from pixels ineach area, can be set. Further, the output in each area can be obtainedbased on an output from one pixel in each area. This determinationprocessing is performed by the processing unit 110 illustrated in FIG. 1, but instead a determination circuit can be provided in a readoutcircuit of the receiver 102. In the manner as described above, atransmission unit inspection operation can be performed.

FIG. 3A is a flowchart illustrating the transmission unit inspectionoperation. First, in step S300, an operating state of each transmissionunit is checked. In this step, it is checked whether each transmissionunit irradiates a terahertz wave. Depending on the operating state, asub-flow for switching an operation of the transmission unit can beperformed. Further, an operation flow for skipping the subsequent stepS301 depending on the operating state can be added. In step S301, theirradiation of terahertz waves is started. The transmission units 103 to105 operate to irradiate terahertz waves. In a case where thetransmission units 103 to 105 are already in an irradiation state, theirradiation state is maintained. The irradiation state is also referredto as a light state. In step S302, images of the transmission units 103to 105 are captured. The reception unit 100 detects the terahertz wavesirradiated from the transmission units 103 to 105. The image acquired inthe irradiation state is also referred to as a light image. In stepS303, it is determined whether the output of each of the transmissionunits 103 to 105 is more than or equal to a threshold based on adetected signal or an image based on the signal. In a case where theoutput is more than or equal to the threshold (Yes in step S303), theinspection is completed. In a case where the output is less than thethreshold (No in step S303), the processing proceeds to step S304. Instep S304, for example, the processing unit 110 issues an instructionand displays a warning on the display unit 111. In addition, in a casewhere the output is less than the threshold (N in step S303), forexample, the processing unit 110 can perform an operation to issue analert sound. This operation enables checking of the operation of each ofthe transmission units 103 to 105 that cannot be visually recognized.

In some cases, spatial noise or shading may be superimposed on the imageillustrated in FIG. 2B due to the circuit of the receiver 102. In thiscase, the following operation is to be performed. FIG. 3B is a flowchartillustrating another operation to be executed in the transmission unitinspection operation. In FIG. 3B, the descriptions of operations similarto those illustrated in FIG. 3A are omitted. In step S311, theirradiation of terahertz waves is stopped. For example, the operation ofeach of the transmission units 103 to 105 is stopped to thereby stop theirradiation of terahertz waves. Alternatively, the transmission units103 to 105 operate to stop the irradiation of terahertz waves. Morealternatively, a member for blocking terahertz waves is disposed infront of the transmission units 103 to 105. In a case where thetransmission units 103 to 105 are already in a non-irradiation state,the non-irradiation state is maintained. The non-irradiation state isalso referred to as a dark state. In step S312, images of thetransmission units 103 to 105 are captured in the non-irradiation state.Each of the images captured in the non-irradiation state is alsoreferred to as a dark image. Then, the operations in steps S301 and S302are performed. In step S313, signal processing is performed. In thesignal processing, processing for removing information about the darkimage from information about the light image is performed. The darkimage is referred to as a reference signal. In other words, in thesignal processing, the reference signal is removed from the light image.In step S303, the determination is made in a state where the signalprocessing has been performed, and then the processing is completed, orstep S304 is executed. This processing leads to a reduction in noise andan improvement in the accuracy of the determination in step S303. Theimprovement in determination accuracy leads to an improvement in theaccuracy of detecting a malfunction in the transmission units 103 to105.

If noise randomly occurs during a predetermined period of time, thefollowing operation can be performed. In the operation flow illustratedin FIG. 3A, step S302 can be performed a plurality of times and aplurality of light images can be averaged. Step S302 can be performedbased on the averaged image. In the operation flow illustrated in FIG.3B, if noise randomly occurs during a predetermined period of time, stepS312 can be performed a plurality of times and a plurality of darkimages can be averaged. In step S313, information about the averageddark image can be removed from the light image. Further, in theoperation flow illustrated in FIG. 3B, if noise randomly occurs during apredetermined period of time, each of steps S302 and S312 can beperformed a plurality of times, and then a plurality of light images canbe averaged and a plurality of dark images can be averaged. In stepS313, information about the averaged dark image can be removed from theaveraged light image. This processing makes it possible to reduce noisethat randomly occurs during a predetermined period of time.Consequently, it is possible to improve the accuracy of detecting amalfunction in the transmission units 103 to 105.

In steps S301 and S302, the following operation can be performed. Forexample, in step S301, all the transmission units 103 to 105 can bebrought into the irradiation state, and then step S302 can be performed.Alternatively, the transmission units 103 to 105 can be brought into theirradiation state from the non-irradiation state by rotation, and animage capturing operation can be performed every time any of thetransmission units 103 to 105 is brought into the irradiation state. Inother words, steps S301 and S302 are performed a plurality of times bychanging the operating state of each of the transmission units 103 to105. First, in step S301, the transmission unit 103 is brought into theirradiation state, and the transmission unit 104 and the transmissionunit 105 are brought into the non-irradiation state. Then, step S302 isperformed. Step S301 is performed again, and the transmission unit 103and the transmission unit 105 are brought into the non-irradiation stateand the transmission unit 104 is brought into the irradiation state.Then, step S302 is performed. Step S301 is performed again, and thetransmission unit 103 and the transmission unit 104 are brought into thenon-irradiation state and the transmission unit 105 is brought into theirradiation state. Then, step S302 is performed. Not only thetransmission units 103 to 105, but also the transmitters 106 to 108 canbe sequentially turned on and the image capturing operation can beperformed every time this turning-on operation is performed.Alternatively, the image capturing operation can be performed by turningon a specific transmission unit or transmitter as an inspection target.

The image capturing operation in respective steps S302 and S312 can bean operation of capturing one frame (still image), a plurality ofdiscontinuous frames, or temporally continuous frames (moving image). Inthe case of capturing a moving image, data corresponding to one framecan be extracted from the image and the extracted data can be processed.

Information about the number of transmission units and transmitters andan arrangement relationship between the transmission units andtransmitters can be preliminarily held in the processing unit 110.Examples of the information include information indicating that thethree transmission units 103 to 105 each including four transmittersdisposed in an array of 2×2 are aligned. Based on this information, eachtransmission unit and each transmitter can be extracted from thecaptured images of the transmission units and transmitters. Eachtransmission unit and each transmitter can also be extracted from theimages using the AI. The AI can be provided in the processing unit 110,a cloud system, or the like. This processing enables the display unit111 to display the state of each of the transmission units 103 to 105.Therefore, at least one of an improvement in the efficiency of thetransmission unit inspection operation and an improvement in theconvenience of the transmission unit inspection operation can beachieved.

The camera system 1001 can include an extra transmission unit (notillustrated). After step S304, the extra transmission unit can beswitched to be operated. After step S304, the output of each of thetransmission units 103 to 105 can also be increased.

The flow of the transmission unit inspection operation illustrated inFIGS. 3A and 3B can be carried out, when the camera system 1001 isinstalled in a place for operation, when maintenance work isperiodically performed, or when the operation of the camera system 1001is started. Such flow can be carried out every time the main imagecapturing operation is performed. In other words, after step S304, theprocessing can transition to the main image capturing operation.

The dark image acquired in step S312 can also be acquired by bringingthe transmission units 103 to 105 into a transmission state. In thiscase, a method for preventing the reception unit 100 from being directedtoward the transmission units 103 to 105 is to be provided, or thereception unit 100 or the transmission units 103 to 105 are to beprovided with a blocking unit for blocking terahertz waves, and when thedark image is acquired, the blocking unit are moved to a space betweenthe reception unit 100 and the transmission units 103 to 105. Thisoperation makes it possible to acquire the dark image in a state whereterahertz waves are not incident on the reception unit 100. This methodcan be carried out in a case where the operation of the transmissionunits 103 to 105 or the other portion is unstable due to the operationof switching the state of each of the transmission units 103 to 105.

A camera system 1002 according to a second exemplary embodiment will bedescribed with reference to FIGS. 4A and 4B.

FIG. 4A is a schematic diagram illustrating a configuration example ofthe camera system 1002. A configuration of an optical system in thecamera system 1002 is different from that of the camera system 1001according to the first exemplary embodiment. An optical system 401 has aconfiguration in which an adjustment mechanism 402 for adjusting a focusis added to the optical system 101 illustrated in FIG. 1 . Components ofthe second exemplary embodiment that are the same as those of the firstexemplary embodiment are denoted by the same reference numerals anddetailed descriptions thereof are omitted.

The adjustment mechanism 402 can focus the object 109 when an image ofthe object 109 is captured, and can focus the transmission units 103 to105 when the transmission unit inspection operation is performed.

FIG. 4B illustrates an image captured by the camera system 1002illustrated in FIG. 4A. Reference numerals used in FIG. 4B are the sameas those used in FIG. 2B. The adjustment mechanism 402 can perform theimage capturing operation by focusing an electromagnetic wave on each ofthe transmission units 103 to 105. Accordingly, a clearer image i.e., anoutput with higher precision than that of the first exemplary embodimentcan be obtained.

With this configuration, the transmission unit inspection operation canbe performed with high accuracy even in a layout in which a distancefrom the reception unit 100 to the transmission units 103 to 105 isdifferent from a distance from the reception unit 100 to the object 109.Further, the degree of freedom of installation of the transmission units103 to 105 can be improved.

A camera system 1003 according to a third exemplary embodiment will bedescribed with reference to FIGS. 5A to 5C.

FIG. 5A is a schematic diagram illustrating a configuration example ofthe camera system 1003. The camera system 1003 has a configuration inwhich a movable unit 500 that changes an orientation of the receptionunit 100 is added to the camera system 1001 according to the firstexemplary embodiment. Further, the camera system 1003 differs from thecamera system 1001 in regard to the number of transmission units and thelayout of the transmission units. Components of the third exemplaryembodiment that are the same as those of the first exemplary embodimentare denoted by the same reference numerals and detailed descriptionsthereof are omitted.

The camera system 1003 includes transmission units 501 to 506. Thetransmission units 501 to 503 are grouped as a set of transmissionunits, and the transmission units 504 to 506 are grouped as another setof transmission units. The object 109 is located between the set of thetransmission units 501 to 503 and the set of the transmission units 504to 506. The reception unit 100 is located between the set of thetransmission units 501 to 503 and the set of the transmission units 504to 506. The movable unit 500 is a member that changes the imagecapturing direction of the reception unit 100 and also supports thereception unit 100. In the case of performing the transmission unitinspection operation on the transmission units 501 to 503, the movableunit 500 is rotated in a direction A. In the case of performing thetransmission unit inspection operation on the transmission units 504 to506, the movable unit 500 is rotated in a direction B. The movable unit500 receives a signal from the processing unit 110 and operates inresponse to the signal. The movable unit 500 can communicate with theprocessing unit 110. In the configuration illustrated in FIG. 5A, themovable unit 500 communicates with the processing unit 110 through thereception unit 100, but instead can directly communicate with theprocessing unit 110.

FIGS. 5B and 5C illustrate images captured with the configurationillustrated in FIG. 5A. FIG. 5B illustrates images captured when themovable unit 500 is rotated in the direction A. FIG. 5C illustratesimages acquired when the movable unit 500 is rotated in the direction B.FIG. 5B illustrates the images corresponding to the transmission units501 to 503, respectively. FIG. 5C illustrates the images correspondingto the transmission units 504 to 506, respectively. Each white areacorresponds to a transmitter in each transmission unit. The provision ofthe movable unit 500 having a configuration as described above makes itpossible to inspect a plurality of transmission units located inmultiple directions by using one reception unit 100. As illustrated inthe layout of FIG. 5A, in a case where an irradiation surface of each ofthe transmission units 501 to 506 and a reception surface of thereception unit 100 do not face each other, the output of each of thetransmission units 501 to 506, which is detected by the reception unit100, may be decreased due to a directivity of each of the transmissionunits 501 to 506 and the cosine law. In this case, signal processing tocorrect the output before the output is determined is performed.Alternatively, the threshold value is to be changed. During the imagecapturing operation, images can be continuously captured while themovable unit 500 is moved in the direction A or in the direction B. Likein the second exemplary embodiment, the optical system 101 can beprovided with the adjustment mechanism 402, or a wide angle lens can beused. In this case, a plurality of transmission units can be captured inone image, but the resolution of each transmission unit is decreased.Accordingly, it is desirable to carry out the image capturing operationby taking into consideration the number of pixels.

During the transmission unit inspection operation, a reflecting membercan be provided at a position corresponding to the object 109. Thereflecting member makes terahertz waves, which are irradiated from thetransmission units 501 to 506, be reflected, and the reflected waves canbe detected by the reception unit 100. It is also possible to inspectthe light source in a state where an image of a front surface of eachtransmission unit is captured by adjusting the position or angle of thereflecting member.

The movable unit 500 according to the present exemplary embodiment canperform a rotational operation in the direction A or in the direction B,i.e., can move in a horizontal direction, but instead can move in anydirection including a vertical direction. The structure of the movableunit 500 can also be applied to a general structure.

As described above in the present exemplary embodiment, the provision ofthe movable unit 500 that changes the image capturing direction makes itpossible to effectively inspect a plurality of transmission unitslocated in multiple directions.

A camera system 1004 according to a fourth exemplary embodiment will bedescribed with reference to FIG. 6 .

FIG. 6 is a schematic diagram illustrating a configuration example ofthe camera system 1004. The camera system 1004 has a configuration inwhich another reception unit 600 is added to the camera system 1001according to the first exemplary embodiment. Components of the fourthexemplary embodiment that are the same as those of the first exemplaryembodiment are denoted by the same reference numerals and detaileddescriptions thereof are omitted. In FIG. 6 , the processing unit 110and the display unit 111 are not illustrated.

Like the reception unit 100, the reception unit 600 includes an opticalsystem 601 and a receiver 602. A component 650 that is reflected by theobject 109 and is included in the terahertz waves generated from thetransmission units 103 to 105 is imaged on the receiver 602, and thereceiver 602 detects a signal. In the present exemplary embodiment, thereflected wave from the object 109 is detected. Accordingly, thetransmission units 103 to 105, the object 109, and the reception unit600 are located in a V-shape as illustrated in FIG. 6 . In other words,a direction connecting the transmission units 103 to 105 and the object109 intersects with a direction connecting the object 109 and thereception unit 600. The reception unit 100 is provided to inspect thetransmission units 103 to 105. The transmission unit inspectionoperation can be performed at a timing when the object 109 is notpresent.

With this configuration, the reception unit 600 that captures an imageof the object 109 and the reception unit 100 that performs thetransmission unit inspection operations are separately provided.Accordingly, each configuration can be simplified, for example, byfixing the focus or image capturing direction, and the transmission unitinspection operation and the image capturing operation can beeffectively performed.

A camera system 1005 according to a fifth exemplary embodiment will bedescribed with reference to FIGS. 7 to 8D.

FIG. 7 is a schematic diagram illustrating a configuration example ofthe camera system 1005. The camera system 1005 has a configuration inwhich a reception unit 700 and transmission units 703 to 705 are addedto the camera system 1001 according to the first exemplary embodiment.The reception unit 100 captures an image of a back surface of the object109, and the reception unit 700 captures an image of a front surface ofthe object 109. Components of the fifth exemplary embodiment that arethe same as those of the first exemplary embodiment are denoted by thesame reference numerals and detailed descriptions thereof are omitted.In FIG. 7 , the processing unit 110 and the display unit 111 are notillustrated. FIGS. 8A to 8D illustrate images captured with theconfiguration illustrated in FIG. 7 . The components illustrated in FIG.8A that correspond to those illustrated in FIG. 2B are denoted by thesame reference numerals.

In the camera system 1005, the units are disposed as follows. Thereception unit 100 is disposed to face the transmission units 103 to105, and the reception unit 700 is disposed to face the transmissionunits 703 to 705. A direction connecting the reception unit 100 and thetransmission units 103 to 105 intersects with a direction connecting thereception unit 700 and the transmission units 703 to 705.

Like the reception unit 100, the reception unit 700 includes an opticalsystem 701 and a receiver 702. A component 750 that is reflected by theobject 109 from the terahertz waves generated from the transmissionunits 103 to 105 is imaged on the receiver 702, and the receiver 702detects the signal.

The operation of the camera system 1005 will be described below withreference to FIG. 3A. In steps S301 and S302, the reception unit 100captures images of the transmission units 103 to 105, and the receptionunit 700 captures images of the transmission units 703 to 705. Based onthe captured images, the transmission units 103 to 105 and thetransmission units 703 to 705 are inspected. Steps S301 and S302 may beexecuted on the transmission units 103 to 105, may be executed on thetransmission units 703 to 705, or may be executed on the transmissionunits 103 to 105 and the transmission units 703 to 705. In any case, thereception unit 100 or the reception unit 700 is used depending on thecase. FIG. 8A illustrates images obtained when the reception unit 100captures images of the transmission units 103 to 105. FIG. 8Billustrates images obtained when the reception unit 700 captures imagesof the transmission units 703 to 705.

In the main image capturing operation, the following operation isperformed. Terahertz waves irradiated from the transmission units 103 to105 are reflected on the front surface of the object 109, and thereflected component 750 is received by the reception unit 700. Thus, animage of the front surface of the object 109 can be acquired. Terahertzwaves irradiated from the transmission units 703 to 705 are reflected onthe back surface of the object 109, and a reflected component 751 isreceived by the reception unit 100. Thus, an image of the back surfaceof the object 109 can be acquired. FIG. 8C illustrates the imageobtained when the reception unit 700 captures an image of the object109. FIG. 8D illustrates the image obtained when the reception unit 100captures an image of the object 109.

In the camera system 1005 capable of capturing images of the frontsurface and the back surface of the object 109, the image of the object109 can be captured and the transmission unit inspection operation canbe performed. This configuration leads to simplification of the entiresystem of the camera system 1005, and makes it possible to effectivelyperform the light source inspection operation.

Some exemplary embodiments of the disclosure have been described above.

However, the disclosure is not limited to the above-described exemplaryembodiments and can be modified or altered in various ways within thescope of the disclosure. The components of the camera systems accordingto the above-described exemplary embodiments can be combined and used.

Further, in each exemplary embodiment, operations to be performed by thereception units, the transmission units, and the movable unit can beconverted into a system to be automatically controlled. Specificexamples of the operations include turning on/off operations of thetransmission units, an operation of changing the image capturingdirection by rotating the movable unit, focus adjustment and imagecapturing operations of the reception units, and a periodicaltransmission unit inspection operation. These operations can bearbitrarily combined and automated, which leads to a reduction in humanworkload.

While the disclosure has been described with reference to exemplaryembodiments, it is to be understood that the disclosure is not limitedto the disclosed exemplary embodiments. The scope of the followingclaims is to be accorded the broadest interpretation so as to encompassall such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2020-085565, filed May 15, 2020, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A system comprising: a plurality of transmissionunits configured to generate an electromagnetic wave; a first receptionunit configured to detect the electromagnetic wave; and a processingunit configured to conduct a transmission units inspection operationincluding detecting an image of the plurality of transmission units in astate where the plurality of transmission units is irradiating theelectromagnetic wave, and determining whether an output of theelectromagnetic wave from the plurality of transmission units is morethan or equal to a threshold based on first image information of theimage, wherein in a case where the output is less than the threshold,the processing unit is configured to perform an operation to issue atleast one of an instruction, a warning, and an alert sound.
 2. Thesystem according to claim 1, wherein the electromagnetic wave is aterahertz wave.
 3. The system according to claim 1, wherein theelectromagnetic wave is in a frequency band from 0.1 THz to 30 THz. 4.The system according to claim 1, further comprising an optical systemconfigured to focus the electromagnetic wave on the reception unit. 5.The system according to claim 4, wherein the optical system includes afocus adjustment mechanism.
 6. The system according to claim 1, whereinthe processing unit is configured to control a first operation forcapturing an image of the transmission unit in the state where thetransmission unit is irradiating the electromagnetic wave, and a secondoperation for capturing an image of the transmission unit in a statewhere the transmission unit is not irradiating the electromagnetic wave.7. The system according to claim 6, wherein the first operation includeschecking a state of at least the transmission unit, and capturing animage of the transmission unit in the state where the transmission unitis irradiating the electromagnetic wave, and wherein the secondoperation includes checking a state of at least the transmission unit,and capturing an image of the transmission unit in the state where thetransmission unit is not irradiating the electromagnetic wave.
 8. Thesystem according to claim 6, wherein the processing unit performsprocessing for acquiring the first image information by the firstoperation, acquiring second image information by the second operation,and removing the second image information from the first imageinformation.
 9. The system according to claim 8, wherein the processingunit performs the removing before the determining.
 10. The systemaccording to claim 1, further comprising a movable unit provided withthe reception unit and configured to change an orientation of thereception unit.
 11. The system according to claim 1, further comprisinga second reception unit.
 12. The system according to claim 11, whereinthe processing unit is configured to control a third operation for thesecond reception unit to capture an image of an object.
 13. The systemaccording to claim 12, further comprising an optical system configuredto focus the electromagnetic wave on the first reception unit.
 14. Thesystem according to claim 13, wherein the optical system includes afocus adjustment mechanism.
 15. A system comprising: a plurality oftransmission units configured to generate an electromagnetic wave; areception unit configured to detect the electromagnetic wave; an opticalsystem configured to include a focus adjustment mechanism and to focusthe electromagnetic wave on the reception unit; a movable unitconfigured to be provided with the reception unit and to change anorientation of the reception unit; and a processing unit configured toconduct a transmission units inspection operation including detecting animage of the plurality of transmission units in a state where theplurality of transmission units is irradiating the electromagnetic wave,and determine whether an output of the electromagnetic wave from theplurality of transmission units is more than or equal to a thresholdbased on first image information of the image, wherein in thetransmission units inspection operation, the movable unit turns thereception unit to the plurality of transmission units, and wherein in acase where the output is less than the threshold, the processing unit isconfigured to perform an operation to issue at least one of aninstruction, a warning, and an alert sound.
 16. The system according toclaim 15, wherein the processing unit is configured to control a firstoperation for capturing an image of the transmission unit in the statewhere the transmission unit is irradiating the electromagnetic wave, anda second operation for capturing an image of the transmission unit in astate where the transmission unit is not irradiating the electromagneticwave, wherein the processing unit performs processing for acquiring thefirst image information by the first operation, acquiring second imageinformation by the second operation, and removing the second imageinformation from the first image information, and wherein the removingis performed before the determining.
 17. A method for a system,comprising: acquiring first image information obtained by capturing animage of a plurality of transmission units in a state where theplurality of transmission units is irradiating an electromagnetic wave;and determining whether an output of the electromagnetic wave from theplurality of transmission units is more than or equal to a thresholdbased on the first image information of the image; wherein in a casewhere the output is less than the threshold, an operation to issue atleast one of an instruction, a warning, and an alert sound is performed.18. The method according to claim 17, further comprising: acquiringsecond image information obtained by capturing an image of thetransmission unit in a state where the transmission unit is notirradiating the electromagnetic wave; and removing a signal based on thesecond image information from a signal based on the first imageinformation.
 19. The method according to claim 18, wherein the removingis performed before the determining.
 20. The method according to claim17, wherein the electromagnetic wave is a terahertz wave.
 21. The methodaccording to claim 17, wherein the electromagnetic wave is in afrequency band from 0.1 THz to 30 THz.
 22. The method according to claim17, further comprising: controlling a first operation for capturing animage of the transmission unit in the state where the transmission unitis irradiating the electromagnetic wave; and controlling a secondoperation for capturing an image of the transmission unit in a statewhere the transmission unit is not irradiating the electromagnetic wave.23. The method according to claim 17, further comprising acquiringsecond image information obtained by capturing an image of thetransmission unit in a state where the transmission unit is notirradiating an electromagnetic wave, and removing the second imageinformation from the first image information, wherein the removing isperformed before the determining.